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In this October 2, 2017 file photo, the W Las Vegas displays a message for the victims of Sunday night's mass shooting, October 2, 2017 in Las Vegas, Nevada. Late Sunday night, a lone gunman killed more than 50 people and injured more than 500 people after he opened fire on a large crowd at the Route 91 Harvest Festival, a three-day country music festival. The massacre is one of the deadliest mass shooting events in U.S. history.

Legal action following the mass shooting at a Las Vegas concert is picking up with lawsuits filed Wednesday on behalf of 14 concertgoers, including some who were shot or injured trying to escape and one woman who is so traumatized that she has since mistaken the sound of rain for gunshots.

The hotel-casino from where Stephen Paddock fired, concert organizers and the makers and sellers of a bump stock gun accessory that enabled him to fire rapidly are named as defendants. The court filings argue that they all share blame for the worst mass shooting in recent U.S. history.

The 14 civil complaints, filed together in state court in Las Vegas, follow at least three others filed since Paddock opened fire Oct. 1 from the 32nd floor of the Mandalay Bay hotel and casino, killing 58 people and injuring hundreds of others. The lawsuit seeks unspecific compensation for both "physical and mental injuries."

The challenge for mass-shooting lawsuits is clearing a high legal bar to prove someone other than the shooter bears any responsibility. Such litigation typically drags for years and can end with victims and their families receiving little to nothing.

One of those suing, Elisha Seng, described in a phone interview haunting images she can't dispel — of bullets thudding around her on the concert grounds and of turning to see a young woman covered in blood after being shot, clutching her throat and falling forward.

"I don't sleep at night and, when I do, I have nightmares," said the 46-year-old from Bartlett, Illinois, just outside Chicago. Recently, as heavy rain began to fall outside overnight, she jumped up from her bed. "I thought it was gunshots."

Seng, who wasn't physically injured, returned to work as a sales representative, but said she quickly tires from her lack of sleep. Going to concert or sports halls can prompt flashbacks. She recently attended a Chicago Blackhawks game and found herself nervously calculating the best escape routes should someone open fire.

A Chicago law firm helped to prepare the filings, which include several plaintiffs from the Chicago area. Victims named in the suits also include a California man, Anthony Crisci, who was rushed to a hospital with a gunshot wound in a truck crowded with dead and injured.

Among deficiencies at the concert venue were poorly marked exits, Wednesday's filings say. And the hotel, it says, should have had gunfire-location devices that pinpoint where shots are coming from.

The 64-year-old Paddock, who killed himself just before his room was stormed, is also named in a bid to seize assets from his estate.

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Paddock was able to use VIP status conferred on him as a high-stakes gambler to stockpile more than 20 rifles in his hotel suite, including by using exclusive access to a service elevator over days, the filings sat. They argue what should have been routine checks of Paddock's bags and his room would have revealed his growing arsenal.

The filings name a leading bump stock maker, Texas-based Slide Fire Solutions, as a defendant. A lead attorney, Chicago-based Antonio Romanucci, said it wasn't yet clear which manufacturer, wholesaler or retailer made and sold the specific bump stock that Paddock used, but that the idea was to hold "the entire supply chain" responsible. Messages seeking comment from Slide Fire weren't returned.

A Wednesday statement from MGM Resorts International, the parent company of Mandalay Bay, called the shooting "a meticulously planned, evil ... act," adding it would respond to any allegations only through "the appropriate legal channels." Live Nation, a concert organizer named, said in a statement it can't comment on pending litigation, adding the company remains "heartbroken for the victims."

Bump stocks were originally created ostensibly to make it easier for people with disabilities to shoot. But the filings allege that Slide Fire geared its marketing to regular gun owners who wanted their semi-automatic rifles to mimic fully automatic weapons.

Civil cases in mass shootings are becoming increasingly common.

Romanucci has also filed a lawsuit on behalf of victims of the Pulse nightclub shooting that killed 49 people last year in Orlando, Florida. It alleges, among other things, that a security firm that once employed gunman Omar Mateen knew Mateen was mentally unstable and had threatened violence, and should have alerted authorities. Mateen was killed in a shootout with police.

The 2007 Virginia Tech campus shooting in which Seung-Hui Cho killed 32 people illustrated the difficulties posed by such lawsuits. In 2013, the Virginia Supreme Court overturned a jury verdict siding with parents of two victims who claimed the state was negligent. A statement from the state attorney general's office at the time said the reversal showed what it had argued during years of litigation: "Cho was the lone person responsible for this tragedy."

Cho killed himself after his rampage.

Seng said she joined the civil case to force better security at concerts and at hotels. She said she can't fathom how a hotel-casino that devotes so many resources to catching gamblers that cheat didn't notice Paddock bringing in high-powered weapons over a number of days.

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